Corn Earworm

Corn Earworm

Helicoverpa zea

This is one of the most common pests of corn in many areas (it is found right across the United States). The adult is a fairly large (1 1/2" - 2" wingspan) light brown moth, the larvae is a 1"-2" yellowish caterpillar. The adults can fly long distances in search of suitable places to lay their eggs. They lay these on the tips of corn ears and the newly hatched larvae burrow down into the ear, eating the silks and then the seeds (they can make quite a mess). Earworms aren’t usually a problem on early Corn, but can affect almost every ear of a late planting. 

Prevention

You can plant corn varieties with tighter husks (i.e. Country Gentleman) as it is harder for the earworms to get inside them. Of course you should always be encouraging predatory insects by planting nectar and pollen producing plants.

Control

Now the good news: Corn Earworm damage is usually confined to the tip of the ear. Usually all you have to do is chop off the damaged tip and the person eating the corn won’t even be aware there was a problem.

Commercial farmers successfully control corn earworm by applying a mix of B.T. and vegetable oil to the silks, but this seems like a lot of work to deal with a relatively minor problem.

Image: Clemson University - USDA Cooperative Extension Slide Series, Bugwood.org